1. Field of the Invention
The present disclosure relates to a system for testing a distortion of a liquid crystal display device, and particularly, to a system for testing a distortion of a liquid crystal display device capable of testing distortion of each component of the liquid crystal display in an assembled state under an actual installation condition of a user.
2. Discussion of the Related Art
Recently, the development of various types of portable electric equipment, such as mobile phones, personal digital assistants (PDAs), and note book computers, is increasing the demands on flat panel display devices which are applicable to those equipment and small in size, light in weight and power-efficient. Examples of the flat panel display device are a liquid crystal display (LCD) device, a plasma display panel (PDP) device, a field emission display (FED) device, a vacuum fluorescent display (VFD) device and the like. Studies on those devices are actively conducted. Among others, the LCD device is currently in the limelight in view of its mass production technology, ease of driving scheme and implementation of high definition.
An LCD device represents information on a screen by use of refractive index anisotropy of liquid crystal. As shown in FIG. 1, an LCD device 1 is provided with a lower substrate 5, an upper substrate 3 and a liquid crystal layer 7 interposed between the lower and upper substrates 5 and 3. The lower substrate 5 is a driving element array substrate. Although not shown, the lower substrate 5 has a plurality of pixels, each of which is provided with a driving element such as a thin film transistor (TFT). The upper substrate 3 is a color filter substrate which has color filter layers for representing actual colors. Also, the lower substrate 5 and the upper substrate 3 are respectively provided with pixel electrodes and common electrodes, and alignment layers for aligning liquid crystal molecules of the liquid crystal layer 7 are coated on the lower and upper substrates 5 and 3.
The lower and upper substrates 5 and 3 are attached to each other by a sealant 9. The liquid crystal layer 7 is interposed therebetween so as to drive the liquid crystal molecules by means of the driving elements formed on the lower substrate 5, thereby controlling the light amount transmitted therethrough, ending up with representation of information.
A fabrication process for the LCD device is divided into a driving element array substrate process of forming driving elements on the lower substrate 5, a color filter substrate process of forming color filter layers on the upper substrate 3, and a cell process, which will be described in conjunction with FIG. 2.
First, a plurality of gate lines and data lines which are arranged on the lower substrates to define a plurality of pixel regions are formed through the driving element array process, and TFTs which are driving elements connected to the gate lines and data lines are formed on each of the pixel regions (S101). Pixel electrodes which are connected to the corresponding TFTs are formed through the driving element array process so as to drive the liquid crystal layer 7 when a signal is applied via the TFTs.
R, G and B color filter layers for representing colors and common electrodes are formed on the upper substrate 3 through the color filter process (S104).
Afterwards, alignment layers are coated on each of the lower substrate 5 and the upper substrate 3. A rubbing process of the alignment layers is followed to provide an anchoring force or a surface adhesive force (i.e., pretilt angle and an alignment direction) to the liquid crystal molecules of the liquid crystal layer 7 formed between the upper substrate 3 and the lower substrate 5 (S102 and S105). Then, a spacer is dispersed on the lower substrate 5 to keep cell gaps constantly, and the sealant 9 is applied to the outer circumference of the upper substrate 3. The lower substrate 5 and the upper substrate 3 are then pressed to be attached to each other (S103, S106 and S107).
The upper and lower substrates 5 and 3 are configured as large glass substrates. That is, a plurality of panel regions are defined on a large glass substrate and the TFT as a driving element and a color filter layer are formed on each panel region. Accordingly, in order to fabricate an individual liquid crystal panel, the glass substrate should undergo cutting and processing processes (S108). Afterwards, liquid crystal is injected into each liquid crystal panel through liquid crystal inlets and the inlets are encapsulated to form a liquid crystal layer. Each liquid crystal panel is tested to complete the liquid crystal panel fabrication (S109 ad S110).
The testing for a liquid crystal panel may be divided into an appearance test, an electrical lighting test, a gravity defect test and a distortion test of the liquid crystal panel and internal components. The lighting test is to determine whether various electric elements are normally operated by applying a signal to each completed liquid crystal panel. The appearance test is to determine whether there is any defect in the liquid crystal panel by examining the liquid crystal panel with the naked eye. The gravity defect test is to determine whether liquid crystal is gathered to a lower portion of the liquid crystal panel due to gravity.
The distortion test of internal components is to inspect the distortion of the liquid crystal panel and the internal components, such as an optical sheet or a diffusion plate, so as to determine whether there is any fault due to the distortion of the internal components. In particular, the distortion test for internal components is carried out under a high temperature and high humid environment, which means the reliability of the LCD device is inspected under severe conditions.
The distortion test three-dimensionally measures a distortion by use of contact type and non-contact type three-dimensional coordinate measuring machines. However, the related art distortion test has the following problems.
First, in order to use the related art three-dimensional coordinate measuring machine, an LCD device should be disassembled so that the distortion of the disassembled components is inspected. However, in this case, such distortion of the internal components cannot be detected in an actually assembled state. Furthermore, a long time is spent to disassemble the LCD device, which causes the requirement of a long time for testing and the increase in cost.
Second, the testing (inspection) is not available under a severe environment. In order to carry out the distortion test for the LCD device under a high temperature and high humidity environment, the high temperature and high humidity environment is first established within a chamber and then the distortion test is possible to be executed. However, the related art three-dimensional coordinate measuring machine is large in size, so it is substantially impossible to carry out the test within the chamber. Hence, after leaving the LCD device within the chamber under a severe environment for a preset time, the LCD device is taken out of the chamber in order to perform the distortion test therefor. Therefore, the testing under the severe environment is substantially impossible to be performed.
Third, the testing is impossible under an actual installation environment of the LCD device. The testing by use of the related art three-dimensional coordinate measuring machine is conducted in a state where a table is disposed at a level with the ground and the LCD device is loaded on the table. Accordingly, since it is different from a condition that the LCD device is actually installed in a user environment (i.e., a condition that the LCD device is disposed horizontal to the ground), a distortion which may occur in the installation environment cannot be detected.